1. Field of the Invention
The present invention relates to a slit width adjusting device and a microscope laser processing apparatus.
2. Description of Related Art
Conventionally, a slit width adjusting device is provided in a laser processing apparatus, and the like, to perform a correction such as a photomask, a flat panel display (FPD), and the like, by laser processing. The slit width adjusting device comprises a variable slit in a light path of a laser light, which is driven by a motor, and the width of the variable slit in the XY direction is adjusted so that the range for which one would like to perform a laser cut matches the slit shape. Thereby, when the laser light is emitted, the laser cut can be performed only for the range which matches the slit shape.
As such a slit width adjusting device, a technique is known in which slit members are in contact, and an original point signal generation electrode which generates an original point signal when the slit width is zero, is attached to the variable slit which is driven by a stepping motor. Thereby, the variable slit is adjusted to a predetermined width based on the original point (see for example, Japanese Patent Application Laid-open Publication No. 2001-208987).
However, in the slit width adjusting device according to the above mentioned Japanese Patent Application Laid-open Publication No. 2001-208987, there has been a problem in that the mechanism thereof is complicated because of the reasons such as a structure in which the slit members are isolated from a linear guide is required, the slit members are required to be provided with the original point signal generation electrode, and the like. Further, the original point signal generation electrodes are in contact with each other repeatedly each time the slit width is adjusted, thus the accuracy of the contacting position is decreased. In addition, a mechanical stability of the device is decreased due to the decreased rigidity and the like of the slit mechanism by the above mentioned contact. Thereby, there is a possibility that a detection accuracy of an original point position (which is the contacting position of the slit members) may be decreased as the detection is repeatedly performed. Moreover, the slit width adjusting device disclosed in Japanese Patent Application Laid-open Publication No. 2001-208987 further has a problem in that the slit width adjustment with a high accuracy has been difficult because the device does not comprise a means to correct the error, and the like, of the stepping motor caused by the mechanism of the slit width adjusting device.